[all-commits] [llvm/llvm-project] 201c4b: [demangler] Rust demangler buffer return

[Nathan Sidwell via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 201c4b9cc4a649e4a54b418749ab5b8bd227e4f0
      https://github.com/llvm/llvm-project/commit/201c4b9cc4a649e4a54b418749ab5b8bd227e4f0
  Author: Nathan Sidwell <nathan at acm.org>
  Date:   2022-04-13 (Wed, 13 Apr 2022)

  Changed paths:
    M lldb/source/Core/Mangled.cpp
    M llvm/include/llvm/Demangle/Demangle.h
    M llvm/lib/Demangle/Demangle.cpp
    M llvm/lib/Demangle/RustDemangle.cpp
    M llvm/tools/llvm-rust-demangle-fuzzer/llvm-rust-demangle-fuzzer.cpp
    M llvm/unittests/Demangle/RustDemangleTest.cpp

  Log Message:
  -----------
  [demangler] Rust demangler buffer return

The rust demangler has some odd buffer handling code, which will copy
the demangled string into the provided buffer, if it will fit.
Otherwise it uses the allocated buffer it made.  But the length of the
incoming buffer will have come from a previous call, which was the
length of the demangled string -- not the buffer size.  And of course,
we're unconditionally allocating a temporary buffer in the first
place.  So we don't actually get buffer reuse, and we get a memcpy in
somecases.

However, nothing in LLVM ever passes in a non-null pointer.  Neither
does anything pass in a status pointer that is then made use of.  The
only exercise these have is in the test suite.

So let's just make the rust demangler have the same API as the dlang
demangler.

Reviewed By: tmiasko

Differential Revision: https://reviews.llvm.org/D123420